Clamping mechanism for the plates of printing machines



A ril 2, 1963 'r. E. PHYTHIAN 3,083,643

CLAMPING MECHANISM FOR THE PLATES OF PRINTING MACHINES Filed July 28, 1961 :s Sheets-Sheet 1 Inventor A ttorn eys April 2, 1963 PHYTHlAN 3,083,643

CLAMPING MECHANISM FOR THE PLATES OF PRINTING MACHINES Filed July 28, 1961 :5 Sheets-Sheet 2 fig;

Inventor A Home y:

P 2, 1963 T. E. PHYTHIAN 3,083,643

CLAMPING MECHANISM FOR ms PLATES 0F PRINTING MACHINES 3 Sheets-Sheet 3 Filed July 28, 1961 Inventor Jmuz/ T W/z) /wm 717w Attorneys United States Patent 3,683,643 CLAPHHIG h/EtIHANiSB/I FOR THE PLATES 0F P'IING MACHINES Thomas E. Phythian, Headingley, Leeds, England, as-

signor to R. W. Crabtree dz Sous Limited Fiied July 28, 1961, Ser. No. 127,518

Claims priority, application Great Britain Aug. 8, 1960 Claims. (Cl. 1ti1378) This invention relates to mechanism for securing the usual stereotype printing plates to the printing cylinders of rotary printing machines. More particularly, the invention is concerned with such mechanism commonly known as tension lock-up mechanism, by which metal of the plate is subjected to a tensional loading instead of a compressional loading as occurs in the older, more usual, method of securing such plates.

In the case of a tension lock-up, the under surface of the printing plate is formed near each of its curved end edges, its straight end edges or (in some cases) near both sets of edges, with a set of undercut recesses: the clamp ing mechanism comprises sets of hooks (one set for each set of recesses), and the mechanism includes some means or other to move the sets of hooks relatively towards one another to enable the plates to be placed in position over the hooks and then relatively apart so as to hold down the plate by a force which tensions the metal of the plate between the opposed sets of hooks.

Due to the nature of the stereotype metal, it is very important that the tension loading of the plate by the hooks shall be more or less uniformly distributed over the plate so as to avoid the setting up of intensified local stresses: such a condition could arise, for example, by the inevitable tolerances or inaccuracies in the formation of the recesses in the plate.

It is the main object of the present invention to provide an improved mechanism which will accommodate itself to any irregularities in the formation of the recesses in the plate in such a manner as to ensure the automatic distribution of the applied operating force more or less uniformly over the extent of the plate.

According to the present invention, the various hooks of a set are mounted for individual movement into plateengaging positions and the various hooks of a set are placed into cooperation with a common operating component or reaction component through floating members which float to balance the pressures exerted by the various hooks of the set against one another so as thereby to distribute the operating or the reaction pressure uniformly among the hooks and hence over the metal of the plate.

As is usual, a set of hooks would be provided for each end of the plate displaced apart circumferentially of the cylinder; however, the sets could be spaced apart longitudinally; a combination of sets of hooks could be provided where it is required to hold down the plate by both circumferential and longitudinal tensions.

The floating members can take various forms but, in general, a member would be provided for each pair of hooks of a set so as to balance the pressure between that pair and those floating members can be carried by another or other floating members which balance the pressure between the diflerent pairs, the final floating member reacting against a common operating or reaction component.

It will be apparent that the hooks are moved positively and do not, by reason of the balanced pressure reaction between hooks, require any springs permitting the hooks to accommodate themselves to one another. it may be desirable to cause the hooks to exert a live clamping action on the plates, in which case it would be suiiicient to operate through a spring which is compressed while the mechanism is operated to secure the plates.

Where, as is commonly the case, the cylinder is required 3,083,643 Patented Apr. 2, i963 to be plated with two or more plates around the cylinder, each of such plates could have a clamp-operating mechanism according to this invention for the hooks at its two straight edges, each being independently operated. Similarly, where the cylinder is required to be plated with two or more plates along the cylinder, the hooks for the various plates could be independently operated by mechanism in accordance with this invention, or operated together from a single operating member.

The invention is illustrated in the accompanying drawings, in which FIGURE 1 is a local plan of the mechanism for operating four hooks to tension a plate circumferentially, FIGURE 2 is a local section on the line II-II of FIGURE 1, and FIGURE 3 a local section on the line IHIII FIGURE 1; FIGURE 4 is a sectional plan view of a slightly modified arrangement for operating two sets of four hooks, which are arranged alongside one another to tension circumferentially two plates laid side by side on a printing cylinder and the various hooks being operable by a common actuating component; FIG- URE 5 is a section taken on the line 11-41 FIGURE 1, and FIGURE 6 an end elevation.

Referring, firstly, to FIGURES l3 of the drawings, the hooks of each of the two pairs are indicated at 1, 2, these hooks each being carried by and mounted to turn on a fixed spindle 3, mounted in blocks 3 in a recess formed in the printing cylinder t, the hooks being formed to engage in recesses cut in a printing plate adjacent one of its longitudinal edges. The hubs of the hooks are fitted with pinions 7, respectively engaged by teeth 8 on curved rack bars 3 one for each pair of hooks and having other rack teeth 9.

The sets of rack teeth 9 for operating the two pairs of hooks 1, 2 are respectively in mesh with a floating pinion 16 mounted on a stud 11, each individual pinion member 10 forming in effect a floating lever interconnecting the two hooks 1, 2 of each pair: the studs 11 are carried at one end of floating lever member 12: this lever is pivotally mounted on a stud 13 between the studs 11 for the two pinions ill.

This stud i3 is mounted on a support 14: in the case of the hooks for the leading (or trailing) end of the plate, this support 14 would usually be fixed to the cylinder: in the case of the other end of the plate, the support would, as is shown in the drawings, be curved about the cylinder 4 and movable circumferentially to cause the various hooks to tension the plate. For this purpose, the support 14 is formed with rack teeth 15 engaging a pinion 16 mounted to turn on a stud l6 secured to the cylinder: this pinion is fast with a pinion 17 in mesh with a rack 3L7 on a bar 18 slidable longitudinally of the cylinder 4. This bar is is arranged to be slidably displaced longitudinaliy on the cylinder 4 by an axially displaceable end ring 19 which operates to move the bar 18 in the plate tensioning direction through a compression spring 20: this causes (through the rack 17 the pinions 17 and 16 and the rack 15) the support 14 to be moved circumferentially of the cylinder so as to effect the operation of the pairs of hooks 1, 2 as has been described.

The mechanism is accommodated in a recess formed in the periphery of the cylinder 4, the recess being closed by a cover plate 21 having openings through which the outer ends of the hooks pass and the floating lever 12 and the support 14- being supported on arcuately faced blocks 22.

Referring now to FIGURES 46 of the drawings, these show a mechanism operating in a similar manner to that described, these drawings, however, showing two complete sets of four hooks, 1, 2-1, 2 for tensioning circumferentially two plates P side-by-side, the arrangement being duplicated, as shown in FIGURE 5, for each circumferential half of the cylinder.

For ease of comparing the two arrangements, the parts of the two constructions which correspond are given the same reference numerals. In place of the pinions 1% coupling the rack bars 8 the rack bars are recessed at their ends at 23 to embrace heads 24 of lever components or members which are pivotally carried between their ends by pivot pins 26 at the opposite ends of the floating lever 12.

It will be clear that, in both arrangements, actuation of the actuating member 19 in the one direction will cause the two supports '14 to move circumferentially about the cylinder 4 carrying with them the floating levers 12 and the bars 8 thus moving the hooks 1, 2 into the grooves in the plate: as the individual hooks engage the end walls of the grooves they will (by the continued actuation of the actuating member 19) build up the force exerted on the plates but if the reaction experienced by any one of each set of four books differs from that of he others, the floating member's (i.e. the parts 12 and the pinions :19 or the components 24) will rock on their pivotal centres so as to equalize the forces exerted by all four hooks thereby achieving a uniform pressure distribution over the width of the plates.

The support 14 serves as a common means for operating the two sets of hooks 1, 1 and 2, 2 through the intermediary of the floating member 12, which is floatingly connected to the support 12 to move both bodily therewith and relatively thereto. The floating member 12. is common to both sets of hooks 1, 1 and 2, 2 in that it transmits operating force to both sets. Similarly, the member 12 acts as a single operating means for transmitting force to the hooks of each set through the intermediary of the individual pinions 1t} and racks 9 in FIGURES l-3, and 6, and through the individual components 24-, and rack bars 8 in FIGURE 4.

The description, so far, given deals mainly with applying the tensional securing force to the hooks for one edge of a plate: for the other edge a similar arrangement of floating members 12, or 12, 24- could be employed but in such a case the part 14 would be secured against movement: however, having regard to the accommodation for plate irregularities which is given by arrangement described for the one edge the other edge of the plate can be held merely by hooks 27 which are as is shown in FIGURE 5 of the accompanying drawings.

As is shown'in FlGUREo, the actuating member can be in the form of a half ring two such half rings being shown for the plates P on the two halves of the cylinder 4-, each half ring being movable endwise on pins 29 by a component 23 of any known type such as an eccentric).

What I claim is: V

1'. Mechanism for securing a printing plate to a rotatable printing cylinder, said rneehanism comprising two hooks engageable with the printing plate; a single operating means; and means floatingly connectingsaid operating iimeans to said hooks and including a floating member connected to said operating means to move both bodily therewith and relatively thereto, and means connecting said floating member respectively to said hooks.

2. Mechanism according to claim 1 in which said floating member is pivotally connected to said operating means.

3. Mechanism according to claim 1 in which the pivotal connection of said floating member to said operating means is between the connections of said floating member to the respective hooks.

4-. Mechanism according to claim 3 in which said floating member is a pinion pivotally connected to said operating means and in which the means connecting said floating member to said hooks comprises racks connected respectively to said hooks and meshing with said pinion on opposite sides or" the pivotal axis thereof.

5. Mechanism according to claim 3 in which said floating member comprises a lever pivoted between its ends to said operating means, the ends of said lever being connected respectively to said hooks.

6. Mechanism according to claim 1 in which said means connecting said floating member respectively to said hooks comprises, for each hook, a pinion connected to said hook to rock therewith; a rack in mesh with said pinion; and means connecting said rack to said floating member.

7. Mechanism according to claim 1 including a spring operatively connected to said single operating means for transmitting operating force to the latter.

8. Mechanism for securing a printing plate to a rotatable printing cylinder, said mechanism comprising two spaced sets of hooks, each of said sets comprising two spaced hooks; a common operating means for both said sets; a common floating member connected to said common operating means to move both bodily therewith and relatively there-to; and separate means respectively connecting said common floating member to said sets, each of said separate means comprising an individual floating'member connected to said common floating member to move both bodily therewith and relatively thereto, and means connecting said individual floating member to the hooks of said set.

9. Mechanism according to claim 8 in which said common floating member comprises a lever pivoted between its ends to said common operating means, the ends of said lever being connected respectively to said separate connecting means.

10. Mechanism according to claim 8 including a spring operatively connected to said common operating means for transmitting operating force thereto.

References Cited in the file of this patent UNITED STATES PATENTS 2,857,841 Worthington et al Oct. 28, 1958 

1. MECHANISM FOR SECURING A PRINTING PLATE TO A ROTATABLE PRINTING CYLINDER, SAID MECHANISM COMPRISING TWO HOOKS ENGAGEABLE WITH THE PRINTING PLATE; A SINGLE OPERATING MEANS; AND MEANS FLOATINGLY CONNECTING SAID OPERATING MEANS TO SAID HOOKS AND INCLUDING A FLOATING MEMBER CONNECTED TO SAID OPERATING MEANS TO MOVE BOTH BODILY THEREWITH AND RELATIVELY THERETO, AND MEANS CONNECTING SAID FLOATING MEMBER RESPECTIVELY TO SAID HOOKS. 